The present invention relates to an image forming system in which an image reading device, image forming device and duplex device are operated a desired combination so as to implement a page printer function, copier function and other functions based on respective applications.
A digital copier extensively used today is an image forming system including an image reading device, image forming device, and duplex device. The image reading device reads a document printed on a document. The resulting image data from the image reading device or image data sent to the system from a host arc applied to the image forming device. The image forming device formats such data in a bit map and outputs them on a sheet. In a duplex mode for forming an on both sides of a sheet, the duplex device image feeds a sheet carrying an image on one side thereof again to the image forming device while turning it over, so that another image may be formed on the other side of the same sheet. With this kind of system, it is possible to construct not only a copier but also a page printer, facsimile apparatus, scanner, electronic file and so forth if the above-mentioned devices are operated in a desired combination. Some advanced digital copiers are loaded with applications for executing such various functions, as needed.
When the image forming system is loaded with a plurality of applications for realizing the functions of various office automation equipment, the applications can share a single resource. Such a system saves cost and space, compared to the installation of individual equipment.
However, the problem with the conventional digital copier or similar image forming system is that it executes single task type system control, i.e., prevents a plurality of applications from executing respective jobs at the same time. Specifically, when a plurality of applications share a single resource, it it likely that a conflict occurs between the applications as to the right to use the resource. Hence, it is impossible with the conventional system to perform multitask type system control which allows two or more applications to execute jobs at the same time.